How will climate change affect the amount, timing, and spatial distribution of rain and snowfall? To prepare for and adapt to a future climate, it is crucial to understand how precipitation patterns will change in response to greenhouse gas emissions. However, observational uncertainty, climate model errors, and an incomplete theoretical understanding make this a challenging prospect. In this talk, I will discuss the physical mechanisms expected to drive large-scale precipitation changes and how well climate models can be expected to capture these processes. I will present new techniques to separate the signal of externally forced climate change from the background noise of purely natural internal climate variability. These techniques reveal that certain “fingerprints” of climate change are apparent in long-term satellite observations of precipitation and suggest that human actions may already be changing global rainfall. I will conclude by discussing the barriers to understanding precipitation changes at the smaller regional scales important for policymakers and outlining how they may be overcome in future research.